20 New Dollars

Taiwan's 20-dollar denomination was introduced in 2001 partly to reduce wear on the 100-dollar note, which the central bank found was cycling through the economy faster than comparable banknotes in neighboring countries. The bimetallic construction was chosen specifically for machine-readability in transit systems — Taipei's MRT network was expanding rapidly at the time and fare gates needed reliable coin discrimination. The denomination never fully displaced the note it was meant to replace.